JEE Main 2026 — d and f Block Elements Question with Solution
JEE Main 2026 (22 January Shift 2)
Question
Among the following oxides of 3 d elements, the number of mixed oxides are 。
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Show full solutionCorrect answer: 3
Correct answer
3
Step-by-step explanation
Mixed oxides contain the same element in two different oxidation states.
Analyzing each oxide:
Ti₂O₃ contains Ti(+3) only - simple oxide.
V₂O₄ contains V(+4) only - simple oxide.
Cr₂O₃ contains Cr(+3) only - simple oxide.
Mn₃O₄ can be written as MnO·Mn₂O₃, containing both Mn(+2) and Mn(+3) - mixed oxide.
Fe₃O₄ can be written as FeO·Fe₂O₃, containing both Fe(+2) and Fe(+3) - mixed oxide.
Fe₂O₃ contains Fe(+3) only - simple oxide.
Co₃O₄ can be written as CoO·Co₂O₃, containing both Co(+2) and Co(+3) - mixed oxide.
Therefore, three mixed oxides are present: Mn₃O₄, Fe₃O₄, and Co₃O₄.
Analyzing each oxide:
Ti₂O₃ contains Ti(+3) only - simple oxide.
V₂O₄ contains V(+4) only - simple oxide.
Cr₂O₃ contains Cr(+3) only - simple oxide.
Mn₃O₄ can be written as MnO·Mn₂O₃, containing both Mn(+2) and Mn(+3) - mixed oxide.
Fe₃O₄ can be written as FeO·Fe₂O₃, containing both Fe(+2) and Fe(+3) - mixed oxide.
Fe₂O₃ contains Fe(+3) only - simple oxide.
Co₃O₄ can be written as CoO·Co₂O₃, containing both Co(+2) and Co(+3) - mixed oxide.
Therefore, three mixed oxides are present: Mn₃O₄, Fe₃O₄, and Co₃O₄.
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